Fix various issues

[joachimvh]

This was easier when I was looking at it anyway then explaining it over text 😉 . After this the server can be started with npx community-solid-server file-search.json or npm start (and with the -f flag if you want to choose the data folder).

Summary of some things:

• The build command was missing a reference to the .componentsignore file. Was also missing the flag that made it so you can write "source" in the config instead of "SearchListener:_source" (last one is not needed anymore once we switch to components.js 5.x). It was also using a prefix that didn't match the repo.
• The EventEmitter import was missing.
• Moved the components.js SearchListener definition to a separate file so it can be imported by other configurations.
• Fixed file-search.json with correct imports and contexts.
• Fixed components.js URLs in package.json (only the major version number is used, rest needs to be 0).

[joepio]

Thank you so much!